In general, a hot-rolled steel sheet is moved and dipped in a plurality of pickling tanks accommodating a pickling solution to remove scale through a chemical reaction with the pickling solution.
As illustrated in FIG. 1, in a related art pickling apparatus for removing scale from a steel sheet, a plurality of pickling tanks 10 are sequentially arranged and a steel sheet 1 is advanced and sequentially dipped in a plurality of pickling tanks 10 to remove scale from the steel sheet.
Concentrations of the pickling solutions respectively accommodated in the plurality of pickling tanks 10 are different. The steel plate 1 is dipped in the forward pickling tank 10 and subsequently transferred to the rear pickling tank 10, and, in this process, since the pickling solution accommodated in the forward pickling tank 10 adheres to the steel plate 1 and the steel plate 1 with the pickling solution of the first pickling tank is introduced to the rear pickling tank 10, a concentration of the rear pickling tank 10 is affected.
Thus, a wringer roll W is disposed between the plurality of pickling tanks 10. The wringer roll W is provided in pairs to press the steel plate 1 upwards and downwards to squeeze out the pickling solution adhering to the steel plate 1 to remove the pickling solution to not be introduced to the rear pickling tank 10.
However, the wringer roll W is formed of a rubber material, and one-sided wear occurs due to a defective shape of the steel plate 1, or the like.
The wringer roll W in which one-sided wear occurs causes the advancing steel plate to zigzag (or skew or meander) to scratch the pickling tank 10 and lower a pickling speed.
Further, the life of the wringer roll W is usually about two months, and productivity thereof is deteriorated due to repair costs and a replacement time, according to maintenance.